pgsql: Delay updating control file to "in production"

Delay updating control file to "in production"

Move the updating of the control file to "in production" status until
the point where WAL writes are allowed.  Before, there could be a
significant gap between the control file update and write transactions
actually being allowed.  This makes it more reliable to use the control
status to verify the end of a promotion.

From: Michael Paquier <michael.paquier@gmail.com>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/ebdf5bf7d1c97a926e2b0cb6523344c2643623c7

Modified Files
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src/backend/access/transam/xlog.c | 31 +++++++++++++++++++++----------
1 file changed, 21 insertions(+), 10 deletions(-)